Uninterruptible power supplies are used to provide backup electrical power to equipment in instances where standard commercial power, or mains power is out of service. Typical uninterruptible power supplies comprise an energy storage unit, such as a battery, to supply backup power to equipment when needed. The stored energy capacity of the battery is maintained by a charging circuit, which charges the battery using mains power. An uninterruptible power supply (UPS) may also include circuitry that is capable of transforming the battery's stored power into a form that is compatible with the equipment receiving the backup power. For example, if an AC powered electric motor requires backup power from the UPS, then the battery's DC power must be converted to an AC form to operate the AC motor. To ensure that power is supplied to the equipment when mains power fails, a switching system within the UPS is provided which disconnects the out-of-service mains power, and connects the battery to the equipment to be operated. This action is reversed when mains power returns to service.
While a UPS may be used for various applications, there are special considerations when a UPS is used in conjunction with a barrier operator that moves an access barrier, such as a garage door, between open and closed positions. Thus, when the barrier operator requires AC power to operate its electric motor, the uninterruptible power source must convert the DC power of the uninterruptible power source's backup battery into AC power, such as 120 VAC at 60 Hz, through the use of a power converter or invertor that includes semiconductor transistor circuitry (i.e. switches). When the converter or invertor is enabled, due to a mains power failure, an oscillator, operating at a predetermined frequency, drives the semiconductor transistors that produce current pulses at the output of the transformer, thereby simulating AC power. As a result, the stored DC energy of the backup battery is continuously converted into AC power until mains power is restored, or the energy storage capacity of the battery is fully depleted. The operation of the oscillator and semiconductor transistors generally have an efficiency of about 50%, and as a result, they consume significant power from the backup battery. This conversion may take place continuously, quickly consuming the stored energy of the backup power source. Thus, there is a need for an uninterruptible power source that can provide backup power to a barrier operator only when it is needed on demand.
Further, users of barrier operators traditionally purchase the barrier operator without considering the additional benefit that an uninterruptible power source may provide. Thus, if the user later desires to add the uninterruptible power source to an already installed barrier operator, he or she may be required to purchase a new barrier operator which has an integrated uninterruptible power source. As a result, the user must needlessly discard a functional barrier operator, while expending additional money and time to purchase and install an entirely new barrier operator that includes the UPS function. Thus, there is a need for an uninterruptible power source that a user can easily attach to an existing barrier operator, in a user-friendly manner.
Additionally, users of barrier operators having a UPS system may reside in geographic regions where temperatures are cold, or where temperatures fluctuate between warm and cold. Under these conditions, the UPS battery may resist being re-charged by the battery charger. As a result, the battery's performance is reduced, thus limiting the time that the barrier operator can be utilized during a mains power failure. Additionally, cold temperatures tend to reduce the useful operating life of the batteries, thus increasing battery replacement frequency and overall cost of ownership. Therefore, there is also a need for a UPS battery heating device, that can maintain the battery's optimal operating temperature while subjected to less than optimum operating temperatures.
Furthermore, uninterruptible power sources currently provided for use with barrier operators do not provide a system for monitoring the status of the battery. As a result, the battery may be in need of replacement, while not having the capacity to operate the barrier operator when the mains power has failed. This is especially problematic if the user solely relies on a garage door as the sole means for entering one's home. In such a case, the user may have to forcibly enter their home, thus incurring the inconvenience and expense needed to make the repairs thereto. Thus, there is a need for a UPS battery monitor that can provide the user with the battery's status or condition, allowing him or her to replace the battery prior to a mains power failure.
Many times when mains power fails, the ambient light outdoors is insufficient to allow safe ingress and egress through the area where the barrier operator and corresponding access barrier are mounted. Because of this, the risk for injury is greatly increased. As a result, there is a need for auxiliary lighting that illuminates a desired area, when mains power has failed, so as to allow safe ingress and egress through the region controlled by the access barrier.